Cash-only H1NI vaccination

It looks like our office may be receiving a shipment of H1N1 vaccinations. In order to more effectively inoculate more people, we would like to offer the shot administration for $20 each (can't charge for the actual vaccine since its free from the government). However, is it in any way fraudulent to do cash-only rather than submitting to insurance? It would be so much easier and we could inoculate so many more people much faster, plus we would get paid! This is how the pharmacies and other flu shot clinics do it, so shouldn't the same rules apply to a doctor's office?

But you have a contract

with insurers so you would be in breach of contract if you make patients pay cash.